The average temperatures were above 25 degrees Celsius, with peaks of 31.2 degrees in Visp, said SF Meteo.
In Basel, temperatures reached 29.3 degrees, in Zurich 28.8 and in Geneva 28.7. In the southern Canton Ticino, 27.8 degrees were recorded in Chiasso.
The heat wave also brought severe thunderstorms and hail near Lausanne, Zurich and in Aarau.
According to the popular daily 20 Minuten, readers sent photographs of ice-covered fields and roads, while temperatures soared up to 30 degrees.